Production of extracellular lipase by the hexachlorocyclohexane utilizing Pseudomonas strain Ptm+

Extracelluar lipase activity was detected in a culture of Pseudomonas strain Ptm⁺ growing on hexachlorocyclohexane. Lipase activity was associated with growth of the bacterium and reached a peak at early idiophase (22 h). Following the lipase activity, bioemulsifier was produced, with maximum activity at mid-idiophase (32 h). The extracellular lipase is probably involved in the extracellular synthesis of the bioemulsifier in the culture broth.     

Climate change at northern latitudes: rising atmospheric humidity decreases transpiration, N-uptake and growth rate of hybrid aspen

At northern latitudes a rise in atmospheric humidity and precipitation is predicted as a consequence of global climate change. We studied several growth and functional traits of hybrid aspen (Populus tremula L.×P. tremuloides Michx.) in response to elevated atmospheric humidity (on average 7% over the ambient level) in a free air experimental facility during three growing seasons (2008-2010) in Estonia, which represents northern temperate climate (boreo-nemoral zone). Data were collected from three humidified (H) and three control (C) plots, and analysed using nested linear models. Elevated air humidity significantly reduced height, stem diameter and stem volume increments and transpiration of the trees whereas these effects remained highly significant also after considering the side effects from soil-related confounders within the 2.7 ha study area. Tree leaves were smaller, lighter and had lower leaf mass per area (LMA) in H plots. The magnitude and significance of the humidity treatment effect - inhibition of above-ground growth rate - was more pronounced in larger trees. The lower growth rate in the humidified plots can be partly explained by a decrease in transpiration-driven mass flow of NO(3) (-) in soil, resulting in a significant reduction in the measured uptake of N to foliage in the H plots. The results suggest that the potential growth improvement of fast-growing trees like aspens, due to increasing temperature and atmospheric CO(2) concentration, might be smaller than expected at high latitudes if a rise in atmospheric humidity simultaneously takes place.     

Characterization of the pollen growth transition in self-incompatible <Emphasis Type="Italic">Petunia inflata</Emphasis>

In Petunia inflata, as in other species that shed bicellular pollen, early pollen tube growth in the pistil is slow, then increases 2- to 5-fold depending on the genotype of the female parent. We refer to the time point at which pollen tubes enter the accelerated phase of growth as the pollen growth transition (PGT). Here, we present evidence that pre-PGT and post-PGT growth are quantitatively and qualitatively different, and that the PGT is triggered when pollen tubes reach the transition zone (TZ) below the stigma. The capacity of various pistil zones to precipitate the PGT was tested through 'stump' pollinations: varying lengths of the pistil apex were excised, the cut surface of the remaining pistil (the stump) coated with stigmatic exudates then dusted with compatible pollen. Pollen applied to TZ tissues entered the PGT earlier than pollen growing in intact control pistils; the PGT was delayed in stylar stumps, largely because of delayed germination and reduced pre-PGT growth. In immature pistils, the PGT was delayed by several hours relative to its onset in mature pistils. The PGT fails to occur in pollen cultured in vitro. Collectively, the data suggest that pollen tubes become competent to enter the PGT when they reach a critical size, but the physicochemical environment of the transmitting tissue is necessary for triggering the cellular changes that result in accelerated growth. An analysis of the distribution of pollen tube tips before and after the PGT suggests that pollen competition is most intense during the pre-PGT phase.     

Combination treatment of elevated UVB radiation,CO2 and temperature has little effect on silver birch (Betula pendula) growth and phytochemistry

Elevations of carbon dioxide, temperature and ultraviolet‐B (UBV) radiation in the growth environment may have a high impact on the accumulation of carbon in plants, and the different factors may work in opposite directions or induce additive effects. To detect the changes in the growth and phytochemistry of silver birch (Betula pendula) seedlings, six genotypes were exposed to combinations of ambient or elevated levels of CO₂, temperature and UVB radiation in top‐closed chambers for 7 weeks. The genotypes were relatively similar in their responses, and no significant interactive effects of three‐level climate factors on the measured parameters were observed. Elevated UVB had no effect on growth, nor did it alter plant responses to CO₂ and/or temperature in combined treatments. Growth in all plant parts increased under elevated CO₂, and height and stem biomass increased under elevated temperature. Increased carbon distribution to biomass did not reduce its allocation to phytochemicals: condensed tannins, most flavonols and phenolic acids accumulated under elevated CO₂ and elevated UVB, but this effect disappeared under elevated temperature. Leaf nitrogen content decreased under elevated CO₂. We conclude that, as a result of high genetic variability in phytochemicals, B. pendula seedlings have potential to adapt to the tested environmental changes. The induction in protective flavonoids under UVB radiation together with the positive impact of elevated CO₂ and temperature mitigates possible UVB stress effects, and thus atmospheric CO₂ concentration and temperature are the climate change factors that will dictate the establishment and success of birch at higher altitudes in the future.     

The first report of autochthonous non-vector-borne transmission of canine leishmaniosis in the Nordic countries

Background

Leishmania spp. are zoonotic protozoans that infect humans and other mammals such as dogs. The most significant causative species in dogs is L. infantum. In dogs, leishmaniosis is a potentially progressive, chronic disease with varying clinical outcomes. Autochthonous cases of canine leishmaniosis have not previously been reported in the Nordic countries.

Results

In this report we describe the first diagnosed autochthonous cases of canine leishmaniosis in Finland, in which transmission via a suitable arthropod vector was absent. Two Finnish boxers that had never been in endemic areas of Leishmania spp., had never received blood transfusions, nor were infested by ectoparasites were diagnosed with leishmaniosis. Another dog was found with elevated Leishmania antibodies. A fourth boxer dog that had been in Spain was considered to be the source of these infections. Transmission occurred through biting wounds and semen, however, transplacental infection in one of the dogs could not be ruled out.Two of the infected dogs developed a serious disease and were euthanized and sent for necropsy. The first one suffered from membranoproliferative glomerulonephritis and the second one had a chronic systemic disease. Leishmania sp. was detected from tissues by PCR and/or IHC in both dogs. The third infected dog was serologically positive for Leishmania sp. but remained free of clinical signs.

Conclusions

This case report shows that imported Leishmania-infected dogs may pose a risk for domestic dogs, even without suitable local arthropod vectors.

     

Evaluation of Bioremediation Treatments in a Shoreline-Simulating Microcosm

A microcosm test was designed to study the efficiency of bioremediation treatments at oil contaminated shorelines. The biodegradation in the hermetically closed microcosm was monitored by measuring the total cumulative inorganic carbon evolved during the bioremediation process. The effects of three different additives, medium-release methylene urea (MU) + apatite, fast-release MU + superphosphate, and a biosorbent, on the biodegradation of weathered crude oil (North Sea Brent) were evaluated at +10°C. All the additives significantly increased mineralization. The total amount of inorganic carbon evolved during the 10-week study was measured in the microcosm treated with oil, and with oil and medium-release MU + apatite, fast-release MU + superphosphate, and biosorbent. The amounts were 40,670,490, and 580 mg, respectively. The respirometric measurements were supported by microbiological determinations, ATP content in the sand, number of heterotrophic bacteria, and amount of biomass-C determined by the substrate-induced respiration method. Nutrient analysis indicated that biodegradation was nitrogen limited. The microcosm test proved to be suitable for comparing the effectiveness of different treatments in enhancing the biodegradation of crude oil-contaminated shores.     

Optical Properties and Light Climate in Lake Verevi

The optical properties and light climate during the ice-free period in the highly stratified Lake Verevi (Estonia) have been studied together with other lakes in same region since 1994. The upper water layer above the thermocline belongs to class “moderate” by optical classification of Estonian lakes but can turn “turbid” (concentration of chlorophyll a up to 73 mg m⁻³ and total suspended matter up to 13.2 g m⁻³) during late summer blooms. In the blue part of the spectrum, light is mainly attenuated by dissolved organic matter and in red part notably scattering but also absorption by phytoplanktonic pigments effect the spectral distribution of underwater light. Consequently, the underwater light is of greenish-yellow color (550–650 nm). Rapid change in optical properties occurs with an increase of all optically active substances close to thermocline (2.5–6 m). Optical measurements are often hampered beneath this layer so that modeling of the depth distribution of the diffuse attenuation coefficient is an useful compliment to field measurements. K_d,PAR ranges from 0.8 to 2.9 m⁻¹ in the surface layer, and model results suggest that it may be up to 5.8 m⁻¹ in the optically dense layer. This forms a barrier for light penetration into the hypolimnion.     

Somatic progenitor cell vulnerability to mitochondrial DNA mutagenesis underlies progeroid phenotypes in Polg mutator mice

Somatic stem cell (SSC) dysfunction is typical for different progeroid phenotypes in mice with genomic DNA repair defects. MtDNA mutagenesis in mice with defective Polg exonuclease activity also leads to progeroid symptoms, by an unknown mechanism. We found that Polg-Mutator mice had neural (NSC) and hematopoietic progenitor (HPC) dysfunction already from embryogenesis. NSC self-renewal was decreased in vitro, and quiescent NSC amounts were reduced in vivo. HPCs showed abnormal lineage differentiation leading to anemia and lymphopenia. N-acetyl-L-cysteine treatment rescued both NSC and HPC abnormalities, suggesting that subtle ROS/redox changes, induced by mtDNA mutagenesis, modulate SSC function. Our results show that mtDNA mutagenesis affected SSC function early but manifested as respiratory chain deficiency in nondividing tissues in old age. Deletor mice, having mtDNA deletions in postmitotic cells and no progeria, had normal SSCs. We propose that SSC compartment is sensitive to mtDNA mutagenesis, and that mitochondrial dysfunction in SSCs can underlie progeroid manifestations.